In recent years, minimization technology has been used extensively for wiring and so forth to meet the need for reduction in the circuit area and increase in the performance of semiconductor memories and system LSI devices, and latest lithographic techniques will be presently used, in particular, for the microfabrication of contact holes connecting wiring layers. On the other hand, transistors with superior high-frequency characteristics require minute gate electrodes, and transistors having minute gate electrodes, and especially compound semiconductors, are useful for signal processing (optical communication) as well as for the transmission and reception of submillimeter and millimeter waves. For devices requiring superior high-frequency characteristics, in particular, the gate length has been decreased intensively by electron beam lithography.
Minute apertures have been formed conventionally by decreasing the wavelength of exposure light source or reducing the size of electron beams. Alternatively, the aperture length has been decreased by heat-treating a resist or different types of resists have been mixed.
However, decreasing the wavelength of the light source to form minute resist apertures is costly, because the equipment and masks are expensive.
For the use of the electron beam exposure technology to form minute apertures, apertures with an aperture length of 0.05 μm or less have been obtained by improving the accuracy of beam forming, though throughput and stability problems remain. Therefore there is a need for a technique to form a minute aperture by electron beam lithography equipment using an inexpensive light source or having a stable technical level, but the amount of reduction in the aperture length has been limited to 0.05 μm with conventional resist deformation (heat treatment, mixing) technology.
It is an object of the present invention to provide, with respect to a resist using short-wavelength light (short-wavelength resist) or a resist using electron beam (electron beam resist), a method of forming a resist allowing for stable shrink effect, the manufacture of a minute aperture and the accurate control of the length thereof, and to provide a semiconductor device and a method of manufacturing the same by applying the above forming method. Concretely, the short wavelength resist is aimed at an accurate aperture reduction of more than 0.1 μm, and the electron beam resist is aimed at an aperture length of 0.05 μm or less.